The mechanism of phospholipid vesicle-mediated membrane protein transfer will be investigated by spectroscopic and biochemical techniques. The physical properties of vesicles and cells which dictate the selectivity of protein transfer will be studied, and chemical, physical, and enzymatic modifications will be sought to alter the types of proteins transferred. We wish to improve the versatility of this process as a means for enrichment or isolation of membrane components, analysis of membrane protein complexes, and selective modification of cell surfaces. Such a technique would be valuable in studies of surface properties and components of abnormal cells.